The modern mobile communication increasingly tends to provide diversified services to users, and as shown in FIG. 1, it is a system architecture diagram of the existing evolved packet system (EPS). In FIG. 1, the user equipment (UE) 101 is a terminal device for receiving data. The evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which comprises a macro base station (eNodeB) providing an interface for accessing a wireless network for the UE. The mobility management entity (MME) 103 is responsible for managing mobile context, session context and security information of the UE. The serving gateway (SGW) 104 provides mainly user plane functions, and the MME 103 and SGW 104 may reside in the same physical entity. The packet data network gateway (PGW) 105 may be responsible for functions such as charging, lawful interception and the like, and it may reside in the same physical entity as the SGW 104. The policy and charging rules function (PCRF) 106 provides quality of service (QoS) policies and charging criterions. The general packet radio service support node (SGSN) 108 is a network node device for providing routing for data transmission in the universal mobile telecommunication system (UMTS). The home subscriber server (HSS) 109 is a home subsystem which the UE belongs to, and is responsible for protecting subscriber information including the current location of the user equipment, the address of the serving node, subscriber security information, the packet data context of the user equipment and the like.